French police on Friday detained a man who turned himself in after two officers were attacked and shot with their own guns, his lawyer said.

Two other suspects remained at large following the assault late Wednesday in a Paris suburb, which drew a flurry of condemnations from government officials but also calls for stepped up efforts to tackle crime.

One of the officers was shot four times and was still in critical condition with a fractured skull on Friday, while the other was shot twice and is more lightly injured.

On Friday, a 28-year-old man known to local police forces presented himself to a station in Versailles, saying he was at the scene at an industrial park where two plain-clothes policemen were carrying out surveillance from their car.

But he said he did not take part in the attack.

"They thought the police were gypsies prowling about, and he called the police to warn them," the man's lawyer, Joseph Cohen-Sabban, told AFP.

After the officers identified themselves, "things got ultra-violent, he doesn't understand what happened, the two others had drunk a lot," the lawyer said.

The assailants beat up the officers before stealing their guns and shooting them at point-blank range.

Sources close to the inquiry say that along with the officers' service weapons, they also stole a radio and a phone, and vandalised their car.

Interior Minister Gerald Darmanin, who visited the officer's commissariat in Cergy-Pontoise on Thursday, denounced a "savage" attack by men "who by all accounts clearly intended to kill."

A study last November by France's national crime observatory (ONDRP) found that 6,002 police agents were wounded in 2018, a 16 percent jump from the previous year, the largest increase since 2009.

Of these, 666 officers were wounded by guns, knives or other weapons, compared with 418 in 2017.